It is known to provide a lawnmower with a mulching attachment, which permits various articles, such as small branches, leaves and other organic material, to be fed into the rotary blades of the lawnmower to cut them up so as to make a soil fertilizer. An example of such an attachment is disclosed in Canadian Pat. No. 623,020, issued July 4, 1961. This attachment must, however, be installed on the lawnmower, when needed, and removed therefrom when the mower is used for cutting the grass. This operation is therefore time-consuming.